Anisotropic films comprising polymerized liquid crystal (LC) material with uniform orientation are known in prior art. They are typically used as retardation, compensation or polarization films for LC displays or other optical or electrooptical applications. Planar LC films are described for example in WO 98/04651. Homeotropic LC films are described for example in WO 98/00475 and GB 2 324 382 A. Tilted or splayed LC films are described for example in U.S. Pat. No. 5,619,352, WO 97/44409, WO 97/44702, WO 97/44703 and WO 98/12584.
For many applications, e.g., in liquid crystal displays, it is necessary to use as an optical component a stack or multilayer of two or more LC films having the same or different orientation. For this purpose, usually macroscopically aligned LC films are supported on a plastic substrate and are manufactured on a roll to roll coating machine. The polymerized LC films produced are then laminated, e.g., to other LC films or to polarizers.
The lamination process typically involves applying a pressure sensitive adhesive (PSA) sheet to the film, attaching it to the desired component, and then removing the original plastic substrate. If the LC film is to be used with another LC film this must be similarly removed from its supporting substrate. Each lamination stage is both labor and material consumptive. Also, the use of PSA sheets increases the material costs and the thickness of the final multilayer, which is often undesired for use in flat panel displays.
Also, in case of homeotropic films for example often an aluminized plastic substrate is used to induce homeotropic alignment, as described for example in GB 2 324 382 A. In this case, due to the poor adhesion of the aluminum to the surface of the plastic substrate delamination can remove some of the aluminum, leading to an increased defect rate. Also, the homeotropic films thus produced sometimes show a reduced mechanical stability. For example, when a homeotropic LC film thus produced was tested for durability in an environment chamber, it showed a tendency to crack when laminated to other films.